Mailed fed tax return on May 17, but cannot find my info on IRS where's my refund

I mailed my tax return on May 17 via fedex in Cal and was received and signed by a person. But after over 2 months, when I check where's my refund on IRS website, it shows there is no info. I heard that IRS is running behind for processing refund. Is this normal? If this is not normal, what should I do?